Gluten is a protein found in wheat, barley, rye and triticale – it provides structure, elasticity, moisture retention and flavour when used in processing foods such as doughs and breads (1).
Wheat-based foods are also high in FODMAPs (mainly fructans) which are a type of carbohydrate. Fructans are long chains of fructose joined together. They have a role in storing carbohydrates in plant-based products and are found in many foods, such as breads and cereals (particularly those made from wheat, rye and barley), garlic, onion, artichokes, brussels sprouts.
As you can see, gluten and fructans play different roles in foods, and while there are a number of foods that are high in both gluten and fructans, this is not the case for all foods. For example, spelt sourdough is a product that contains minimal fructans, but does contain gluten. See the table below for commonly eaten high vs low FODMAP foods that also contain gluten.
|High FODMAP variety
|Low FODMAP variety
|Wholegrain wheat bread, rye bread
|2 slices spelt sourdough bread, 2 slices gluten free bread, 1 slice oat sourdough bread
|Muesli containing wheat, whole wheat grain biscuit
|Oats* (1/4 cup), quinoa flakes (1 cup), corn flakes (1/2 cup)
|Gluten free pasta (1 cup), quinoa pasta (1 cup)
|Rice cakes – plain (2 rice cakes)
*Note: Depending on where you live, oats may or may not be considered gluten-free. Read our blog about oats here.
Strictly speaking, only those with diagnosed coeliac disease need to be following a strict life-long gluten free diet. Coeliac disease is an autoimmune condition that is characterised by an exaggerated immunological response to ingested gluten. Eating even extremely small amounts of gluten can cause damage to the small intestine, interfering with nutrient absorption, which can have long-term health consequences including osteoporosis and anaemia. Interestingly, despite only up to 1% of the population having coeliac disease, up to 10% of Australians are following a gluten-free diet.
Those individuals following a gluten-free diet due to improvement in gastrointestinal symptoms were originally thought to have non-coeliac gluten sensitivity (NCGS). This is a fairly debated topic, as we are now learning that it may indeed be the FODMAPs, rather than the gluten that is the trigger for these individuals.
Individuals with IBS often report that going on a gluten-free diet improves their symptoms – research done by our group and others is helping to solve the debate surrounding gluten.
We conducted a trial in 2013 where participants with reported NCGS consumed a low FODMAP diet for two weeks, followed by challenges of either a high gluten, low gluten or placebo diet (2). Interestingly, while all participants experienced improved symptoms following the two week low FODMAP period, we could not find any gluten specific effects after they consumed the gluten containing diets (2).
In 2018, a group in Norway found similar results – they provided 59 patients with NCGS muesli bars containing gluten, fructans or placebo, and found that overall symptoms were worse from fructans compared to gluten (3).
Another study this year added to the evidence – participants with IBS were challenged to eat meals either high in FODMAPs, high in gluten or placebo, without knowing what they were receiving, and with a background diet low in FODMAPs and gluten. FODMAPs caused worsened gastrointestinal symptoms for this group, while there was no differences between the placebo and gluten groups (4).
Firstly, if you are someone who reacts to wheat based products but don’t have a diagnosis of IBS or coeliac disease, speak to your doctor who may need to investigate further. Secondly, if you have IBS but think gluten might be causing symptoms, the evidence above suggests it may be the fructans, rather than the gluten. You might like to try spelt sourdough (low FODMAP, but contains gluten) to test this theory on yourself. Last but not least, we always recommend seeking the guidance of a Monash FODMAP trained dietitian who can help to navigate you through a low FODMAP or gluten-free diet, depending on your needs.